There was a free vote. Given Corbyn's longstanding commitment to opposing nuclear weapons, it was perfectly understandable that he could not, in all conscience, vote for Trident. He was aware that his vote would count for nothing since the overwhelming majority of MPs would be voting in favour - and indeed have done.
Are you saying then anniebach that the only person who can stand as a leader of the Labour party must be one who will be prepared to vote against their longstanding and deeply held personal beliefs - even though his/her MPs are also at liberty to vote in accordance with their own, different, beliefs?
Is there no principle whatsoever that you would not be prepared to jettison in order to acquire power? Or are you saying that only people who will be willing to drop even their most deeply held beliefs are appropriate leadership candidates?
Corbyn did vote many times against the Labour Party and up until recently this almost guaranteed he would never achieve high office, with its attendant status and perks. He is, though, very popular with his own constituents and is seen by many as an honourable man.